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Bacterial nucleoid structure and dynamics and its interaction with the membrane

Oleg Krichevsky

Bacterial DNA (nucleoid) is highly compacted. Once the nucleoid is gently removed from bacteria, it expands almost 100-fold and occupies the volume many times that of bacteria. What forces keep the nucleoid in its condensed form inside the bacteria? What are the main features of nucleoid structure and dynamics? How nucleoid interacts with the bacterial membrane?

In collaboration with Prof. Itzhak Fishov, Life Sciences.
 

Figure 1: E. Coli bacteria: the membrane is stained with fluorescent dye Figure 2: The extracted bacterial nucleoid expands to a volume ~ 30 times that of bacteria.

 

Internal dynamics of biological polymers: DNA molecules, actin filaments

Oleg Krichevsky

The problem of polymer dynamics is rather old, going back to the 1930-s.

How the stochastic thermal motion (diffusion) reveals itself in the dynamics of polymer segments which are bound by connectivity along the chain, by polymer stiffness, by topological constrains, by hydrodynamic and other interactions? The question does not have simple solutions either in theory, nor in computer simulations, and neither in experiments. We have developed an original experimental approach to measure the dynamics of biological polymers, such as DNA at the level of single monomer with high temporal and spatial resolution.

Furthermore, one does not have to rely on classical thermal fluctuations to drive the dynamics of the system. We introduce now molecular motors "little nanomachines" which actively push polymers around at the nanoscale.

In collaboration with Dr. Anne Bernheim-Groswasser, Chem. Eng.


Animation 1: The dynamics of a semi-flexible polymer.